If a SIM is offline, Soracom has no way to reach out to the SIM. If the device attempts to connect to a network while the SIM is suspended, Soracom will send a signal to the device informing that the connection is permanently rejected, which will cause the device to stop trying to reconnect.
After manually reactivating a suspended SIM, the device must be manually power cycled in order to resume network connections. Ensure that you have access to the device in order to reboot when reactivating the subscription.
Full details can be found here